loop4: detected capacity change from 0 to 32768 BTRFS: device fsid 395ef67a-297e-477c-816d-cd80a5b93e5d devid 1 transid 8 /dev/loop4 scanned by syz.4.542 (5982) ====================================================== WARNING: possible circular locking dependency detected 5.15.185-syzkaller #0 Not tainted ------------------------------------------------------ syz.4.542/5982 is trying to acquire lock: ffff0000c08908b0 (&type->i_mutex_dir_key#2){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline] ffff0000c08908b0 (&type->i_mutex_dir_key#2){++++}-{3:3}, at: lookup_slow+0x4c/0x80 fs/namei.c:1679 but task is already holding lock: ffff0000ea0b10e0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_free_stale_devices+0x144/0x908 fs/btrfs/volumes.c:603 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&fs_devs->device_list_mutex){+.+.}-{3:3}: __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 insert_dev_extents fs/btrfs/block-group.c:2399 [inline] btrfs_create_pending_block_groups+0x3b4/0xca8 fs/btrfs/block-group.c:2449 __btrfs_end_transaction+0x13c/0x608 fs/btrfs/transaction.c:1016 btrfs_end_transaction+0x24/0x34 fs/btrfs/transaction.c:1052 flush_space+0x400/0xbd8 fs/btrfs/space-info.c:674 btrfs_async_reclaim_data_space+0xe8/0x3f8 fs/btrfs/space-info.c:1169 process_one_work+0x79c/0x1140 kernel/workqueue.c:2310 worker_thread+0x8f4/0x101c kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870 -> #2 (sb_internal#2){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1811 [inline] sb_start_intwrite include/linux/fs.h:1928 [inline] start_transaction+0x624/0x13f0 fs/btrfs/transaction.c:680 btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:793 btrfs_dirty_inode+0xb4/0x1c0 fs/btrfs/inode.c:6436 btrfs_update_time+0x224/0x248 fs/btrfs/inode.c:6478 inode_update_time fs/inode.c:1893 [inline] touch_atime+0x3d0/0x914 fs/inode.c:1966 file_accessed include/linux/fs.h:2521 [inline] btrfs_file_mmap+0xb0/0x11c fs/btrfs/file.c:2449 call_mmap include/linux/fs.h:2177 [inline] mmap_file+0x6c/0xc8 mm/util.c:1092 __mmap_region mm/mmap.c:1784 [inline] mmap_region+0xadc/0x1390 mm/mmap.c:2921 do_mmap+0x67c/0xdb4 mm/mmap.c:1574 vm_mmap_pgoff+0x184/0x284 mm/util.c:551 ksys_mmap_pgoff+0x410/0x620 mm/mmap.c:1623 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline] __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline] __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #1 (&mm->mmap_lock){++++}-{3:3}: __might_fault+0xc8/0x128 mm/memory.c:5357 filldir64+0x2bc/0x9e4 fs/readdir.c:335 dir_emit_dot include/linux/fs.h:3717 [inline] dir_emit_dots include/linux/fs.h:3728 [inline] dcache_readdir+0x140/0x65c fs/libfs.c:196 iterate_dir+0x1f0/0x4cc fs/readdir.c:-1 __do_sys_getdents64 fs/readdir.c:369 [inline] __se_sys_getdents64 fs/readdir.c:354 [inline] __arm64_sys_getdents64+0x11c/0x340 fs/readdir.c:354 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #0 (&type->i_mutex_dir_key#2){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623 down_read+0xc0/0x390 kernel/locking/rwsem.c:1498 inode_lock_shared include/linux/fs.h:797 [inline] lookup_slow+0x4c/0x80 fs/namei.c:1679 walk_component+0x2b0/0x3a8 fs/namei.c:1976 lookup_last fs/namei.c:2431 [inline] path_lookupat+0x13c/0x3d0 fs/namei.c:2455 filename_lookup+0x180/0x414 fs/namei.c:2484 kern_path+0x4c/0x190 fs/namei.c:2582 lookup_bdev+0xbc/0x244 block/bdev.c:982 device_matched fs/btrfs/volumes.c:563 [inline] btrfs_free_stale_devices+0x5d4/0x908 fs/btrfs/volumes.c:608 btrfs_scan_one_device+0x394/0x544 fs/btrfs/volumes.c:1491 btrfs_mount_root+0x404/0x780 fs/btrfs/super.c:1715 legacy_get_tree+0xd4/0x16c fs/fs_context.c:611 vfs_get_tree+0x90/0x274 fs/super.c:1530 fc_mount fs/namespace.c:996 [inline] vfs_kern_mount+0xdc/0x178 fs/namespace.c:1026 btrfs_mount+0x2a0/0x8d4 fs/btrfs/super.c:1811 legacy_get_tree+0xd4/0x16c fs/fs_context.c:611 vfs_get_tree+0x90/0x274 fs/super.c:1530 do_new_mount+0x228/0x810 fs/namespace.c:3010 path_mount+0x5b4/0x1000 fs/namespace.c:3340 do_mount fs/namespace.c:3353 [inline] __do_sys_mount fs/namespace.c:3561 [inline] __se_sys_mount fs/namespace.c:3538 [inline] __arm64_sys_mount+0x514/0x5e4 fs/namespace.c:3538 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 other info that might help us debug this: Chain exists of: &type->i_mutex_dir_key#2 --> sb_internal#2 --> &fs_devs->device_list_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fs_devs->device_list_mutex); lock(sb_internal#2); lock(&fs_devs->device_list_mutex); lock(&type->i_mutex_dir_key#2); *** DEADLOCK *** 2 locks held by syz.4.542/5982: #0: ffff80001480a248 (uuid_mutex){+.+.}-{3:3}, at: btrfs_mount_root+0x1f4/0x780 fs/btrfs/super.c:1708 #1: ffff0000ea0b10e0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_free_stale_devices+0x144/0x908 fs/btrfs/volumes.c:603 stack backtrace: CPU: 0 PID: 5982 Comm: syz.4.542 Not tainted 5.15.185-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call trace: dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2011 check_noncircular+0x240/0x2d4 kernel/locking/lockdep.c:2133 check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623 down_read+0xc0/0x390 kernel/locking/rwsem.c:1498 inode_lock_shared include/linux/fs.h:797 [inline] lookup_slow+0x4c/0x80 fs/namei.c:1679 walk_component+0x2b0/0x3a8 fs/namei.c:1976 lookup_last fs/namei.c:2431 [inline] path_lookupat+0x13c/0x3d0 fs/namei.c:2455 filename_lookup+0x180/0x414 fs/namei.c:2484 kern_path+0x4c/0x190 fs/namei.c:2582 lookup_bdev+0xbc/0x244 block/bdev.c:982 device_matched fs/btrfs/volumes.c:563 [inline] btrfs_free_stale_devices+0x5d4/0x908 fs/btrfs/volumes.c:608 btrfs_scan_one_device+0x394/0x544 fs/btrfs/volumes.c:1491 btrfs_mount_root+0x404/0x780 fs/btrfs/super.c:1715 legacy_get_tree+0xd4/0x16c fs/fs_context.c:611 vfs_get_tree+0x90/0x274 fs/super.c:1530 fc_mount fs/namespace.c:996 [inline] vfs_kern_mount+0xdc/0x178 fs/namespace.c:1026 btrfs_mount+0x2a0/0x8d4 fs/btrfs/super.c:1811 legacy_get_tree+0xd4/0x16c fs/fs_context.c:611 vfs_get_tree+0x90/0x274 fs/super.c:1530 do_new_mount+0x228/0x810 fs/namespace.c:3010 path_mount+0x5b4/0x1000 fs/namespace.c:3340 do_mount fs/namespace.c:3353 [inline] __do_sys_mount fs/namespace.c:3561 [inline] __se_sys_mount fs/namespace.c:3538 [inline] __arm64_sys_mount+0x514/0x5e4 fs/namespace.c:3538 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 BTRFS info (device loop4): using sha256 (sha256-ce) checksum algorithm BTRFS info (device loop4): using free space tree BTRFS info (device loop4): has skinny extents BTRFS error (device loop4): open_ctree failed: -12